Television eeceiveb synchronizing



NOV, 9, 1943. H, LEWIS Re. 22,390

' TELEVISION RECEIVER SYNCHRONIZING SYSTEM Original Filed March 20, 1959 2 Sheets-Sheet l FIG]. IO lz J13 \4 J45 -&

F gg l Y DETECTOR FR gL E JGY REPk O SCINGQ TRANSLATOR AMPLIFIER DEVICE O 1' l n 1 I FE L-J-O c LINE sEPARAToE FREQUENCY GENERATOR 59 o l v [I8 .0 FIELD 1 FRE ENCY GEN RATOR INVENTOR H 0 0 M. LEWIS ATTORNEY Nov- 9, 1943. H. M. LEWIS TELEVISION RECEIVER SYNCHRONIZING SYSTEM 12 Sheets-Sheet 2 Original Filed March 20', 1959 Frlqulncy FIG.6.

m 0 ml! coca-EE- Frequency INVENTOR H LD M. LEWIS BY s g ATTORNEY a single frame or a single complete image.

Reiuued Nov; 9, 1943 STEM Harold M. Lewis, Allenhurst, N. J., assignor to Hazeltine Corporation, a corporation of Delaware Original No. 2,252,599, dated August 12, 1941, Serial No. 262,846, March 20, 1939. Application for reissue March 14, 1942. Serial No. 434,791

24 Claims. (oi. 178-75) 'i'his invention relates to television receivers and particularly to scanning-wave generator synchronizing systems for such receivers.

In television receivers of conventional type, in

order to effect scanning of the target/of a signalreproducing device by the scanning beam, sawtooth current or voltage waves are generated and utilized to produce, respectively. electromagnetic or electrostatic fields of saw-tooth wave form which deflect the beam in two directions normal to each other, thereby to trace upon the target the well-known rectilinear scanning pattern comprising iields of parallel lines. Synchronizing components of the received signal are utilized to control the operation of the scanning-wave generators, thereby to synchronize the scanning action with other related actions in the system. For example, synchronizing impulses or components corresponding to the initiations of successive lines and fields are usually transmitted as a composite synchronizing signal impressed as modulation upon a television carrier wave together with the video-frequency signal. At the receiver, the modulated-carrier wave is detected and the linesynchronizing and field-synchronizing components are separated from the video-frequency signal and from each other and are utilized to synchronize the line-frequency and field-frequency scanning-wave generators with the corresponding apparatus at' the transmitter.

It is highly important that the synchronization be accomplished with precision in order that proper scanning may be obtained. This is especially true in, scanning systems of the interlaced type, where the. field-scanning frequency is not an integral submultiple of the line-scanning frequency smthat the lines of one field interlace or fall between the lines of a preceding field and a plurality of successive fields thus constitute To obtain a precisely interlaced relation between the successivefields, it is especially important that the field trace scansions be initiated at precisely related intervals and without interference from the line-synchronizing components, The; field-synchronizing components must, therefore,

be separated from the composite synchronizing signal before they are utilized to synchronize the ileld scanning-wave generator. Ordinarily, the field-synchronizing components do not interfere with the proper operation oi the line-scanning generator so that the composite synchronizing wave may be applied directly thereto to eflect synchronization. The line-synchronizing and ered to be effectively separated when the fieldsynchronizing components are derived from the composite wave in a form suitable for use independently oi the line-synchronizing components.

It is an object of the present invention, therefore, to provide a television synchronizing system embodying improved means whereby the held-synchronizing components of a composite synchronizing signal may be effectively separated y from the line-synchronizing components.

It is a further object of the invention to provide an improved television synchronizing system of the character described whereby there may be developed eiiectively separated field-synchronizing pulses adapted to synchronize scanningwave generators at the initiation of both the traceand retrace-scanning periods.

In accordance with a feature or the present invention, a television receiver synchronizing system adapted for utilizing a composite synchro- :nizing signal including recurrent line-synchronizing and field-synchronizing components of the same polarity, comprises a synchronizing circuit for a scanning wave generator adapted to be energized by one type oi the components. This system also includes means for delaying the composite signal, for a predetermined period such that certain of the synchronizing components of the other type substantially coincide in time with corresponding components of thecomposite signal without substantially changing the wave form of the delayed signal, and for reversing the relative polarity of the delayed signal with reference to the composite signal. Ths system includes means for combining the delayed-reversedpolarity signal with the unclelayecl signal to develop a resultant signal comprising eiiectively separated synchronizing components of the above-mentioned one type with at'least certain of the synchronizing components of the other type suppressed, as well as means coupling the combining means to the synchronizing circuit.

- The synchronizing circuit of a preferred embodiment of the invention is adapted to he energized at the initiations of both the traceand retracescanning periods by pulses oi opposite polarity developed by the combining means. In various different arrangements utilizing the delay circuit mentionecl' above, and depending on the type oi composite synchronizing signal involved, the delay may be for diiierent periods. For example, it may be equal in duration to half of a linescanning period, to a whole line-scanning period,

or to an integral multiple of the line-scanning field-synchronizing pulses, therefore, are considll period, to obtain different desired results.

In the specification and the appended claims. the term "synchronizing-signal component is employed to describe an amplitude variation of a synchronizing signal which include adeparture from a given value and a subsequent, return to such value after a greater or lesser period. A field-synchronizing component may, for example, comprises. continuous pulseor it'may be serrated in the conventional manner so that it includes a plurality of adjacent pulses.

- For a better understanding or the present invention;v ether with other and further objects thereof, reierence is had, to the following description taken in connection with the accom- P nying drawings, andits scope will be pointed out in the appended claims.

In the accompanying drawings, Fig.1 is a circuit diagram, partially schematic, of a complete television receiving. system including scanping-wave generating and synchronizing apparatus embodying th present invention; Fig. 2 is a circuit diagram of a modified form oithe synchronizing apparatus of Fig. 1; Figs. 3 and 4 are groups 01 curves illustrating the wave forms of synchronizing-signal components utilized and developed in accordance with the present invention, to aid in the understanding thereoirFig. 5

is a frequency diagram; and Figs. 6 and l are curves illustrating certain characteristics oi the apparatus shown in Fig. 2. e v

Referring now more particularly to Fig. fl of the drawings; there is illustrated a television receiving system which may be of either the tuned radio-frequency or superheterodyne type and including, in cascadann antenna-ground system ill, H, a carrier-frequency translator 12, a detector {3, av video-frequency amplifier i l, and

' into an intermediate-irequencysignal and thereupon further selectively amplified. The amplifled-signal irom the translator I2 is delivered to the detector ii in which there are developed modulation-frequency components including the video-frequency and synchronizing-signal components. The modulation-frequency components are supplied to the video-frequency amplifier i4,

wherein they are amplified and from which they are applied in the usual manner to a brilllancycontrol element of the reproducing device II. The modulation-frequency components are also supplied to the separator I8, wherein the composite synchronizing signal is separated from the video-frequency signal. Th composite synchronizing signal is applied directly to the line-scanping generator I! and .also to the separating I apparatus l8, wherein the field-synchronizing components are effectively separated from the composite signal and from which they are applied to the scanning generator I8. The operations oi. the generators l1 and ID are thus synchronized with the corresponding scanning ap-' paratus at the transmitter.

- The intensity or the beam 01' the reproducing device I! is modulated or controlledin accordance with the video-frequency voltages impressed on its control electrode in the usual manner.

Saw-tooth scanning waves are developed by the generators l1 and I8, controlled by the synchronimg-signal components supplied from the units I 8 and I9, and are utilized in the conventional manner to deflect the beam, for example, to

an image-reproducing device is, such as a cathode-ray signal-reproducing tube. Where the receiver is of the superheterodyne type, the conventional frequency changer and intermediateirequency amplifier are included in the carrierfrequency translator I2. A synchronizing-signal output circuits connected to the scanning e183 ments or the device I! in conventional manner. The generator I8 may be of a design. such as is shown in applicants copending application Serial No. 224,023, flied August 10, 1938, and includes a synchronizing or input circuit to which synchronizing' wave components may be applied each comprising two pulses of opposite polarity corresponding to the initiations oi retrace and trace periods, whereby the generator is synchronized at these times. Those parts 01 the system indicated in units Ill-l1, inclusive, may be oi any I conventional construction and operation.

Since the operation 01 the system c! Fig, 1 as.

thus tar described, excepting the apparatus is, is, in general, well understood in th art, a detailed description and explanation thereof is unnecessary. Briefly, however, television modulated-carrier waves are intercepted by the antenna III, II' and selectively amplified in the carrier-frequency translator i2. 0 Where the receiver is of the superheterodyne type. the signals are impressed on a frequency changer-An the translator l2 wherein they are converted and inductance 25in series. The common out-.

produce electric fields oi saw-tooth wave form which deflect the cathode ray of a signal-reproducing tube. in two direction normal to each other so as to trace the usual rectilinear scanning pattern upon the target-of the device. thereby to reconstruct the transmitted picture.

Referring now more particularly to the portion of the system of Fig. l embodying the present invention, the television receiver synchronizing system including the separating apparatus 12 preferably comprises a pair of signal-translating channels including, respectively, vacuum-tube amplifiers 20 and 2|, preferably of the pentode type, having. their input electrodes coupled .in parallel to the output circuit or the separator The anode circuit of tube 2| is coupled, by way oi a delay filter network 22, to a reversing amplifier tube 23. the tubes 20 and 22 having a common output circuitcomprising a resistor 2 put circuit serves as a means for applying synchronizing pulses to the synchronizing circuit of generator |8.- A small capacitance 23a, comprising in whole or in part the inherent circuit capacitance, may be included in shunt with the output circuit 24, .25. The delayfllter network] may be oi'any suitable construction, for example.

a ladder filter comprising series-inductance arms 2| and shunt-condenser arms 21 ,with terminating resistors 28 and 28, as shown. The input terminalsof the network 22 are connected across a load resistor ll of the tube 2! by way of a suitable coupling condenser 2|, the output tenninals of the network 22 being connected to the input electrodes of the tube' 23. The circuit elements of thenetwork 22 may be proportioned to provide a delay of thewave translated thereby of anydesired predetermined duration for effecting suppression of undesired components in the com,- posite signal, as'will presently be explained. In

. one case the delay may be equal to the duration or one-halt a line-scanning period; in another case. to the duration or a whole line-scanning period: and in other cases, to the duration 01' an integral multiple of half line-scanning periods or to any other suitable periods.

Proper operating potentials are supplied to the screens of the tubes 20, II, and 21 from suitable sources indicated at +80, while anodepotentials are supplied to the tubes Ill and 23 by way of their common output circuit 24, 25 and to the tube it by way of the load resistor II, from suitable sources indicated at +3,"

In operation of the apparatus ii, the composite synchronizing signal developed by the separator I8 is impressed on the input circuits of the tubes Ill and 2| and is repeated in their output circuits. synchronizing signal as it appears in the output circuit of each of the tubes 20 and 2| of the apparatus I8 may be as represented by curve A of Fig. 3. This particular wave form is one wellknown form of composite synchronizing signal and includes recurrent'iine-synchronizing components or pulses L, recurrent field-synchronizing components F only one being shown, and additional alternate line-synchronizing components D between line-synchronizing components L and adjacent field-synchronizing components F. That is, the alternate components D alternate with the line-synchronizing components for short periods before and after each field-synchronizing component. The field-synchronizing components in this case are of the same polarity as, but of greater duration than, the line-synchronizing and alternate components and are serrated, as shown, so that, in effect, each fieldsynchronizing component comprises a plurality of successive adjacent pulses. Generator ii is adapted to be synchronized by one of the types of pulses of the wave from A of Fig. 3, specifically, the field-synchronizing pulses F.

The composite synchronizing si nal A is repeated in the output circuits or the tubes 20 and II and from the latter tube it is applied to the delay network 32, whereby it is translated with a predetermined delay, for example, a delay equal to the duration of a one-half line-scanning period, a whole line-scanning period, or a, multiple The delay is such that certain type, specifically, line-synchronizing pulses, subst'antially coincide in time with corresponding components of the original composite signal without substantially changing the wave form of the delayed signal. The delayed wave is thereupon impressed upon the input electrodes of the tube 23 which repeats it in its output circuit with reversed-polarity; that is, the relative polarity of the delayed signal with reference to the undelayed composite synchronizing signal is reversed. The delayed reversed polarity wave, such as is developed when the delay is equal to one-half the duration of a line-scanning period, is illustrated by curve B in Fig. 3. Since this wave is combined with the undelayed wave in the common output circuit of the tubes 20 and 28, certain oi the synchronizing-signal components overlap and thus neutralize each other and there is developed in this common output circuit a resultant wave illustrated by curve Cin Fig. 3. It is seen that the line-synchronizing and alternate components,.just preceding and followin the field-synchronizing components in the delayedand undelayed waves, coincide in timing and, being of opposite polarities, are eife'ctively neutralized or suppressed. Since only the inter- The wave form of the composite mediate portions of the field-synchronizing components of the two waves coincide, only such portions are suppressed and the resultant wave therefor includes two separated pulses indicated at Sr and St for each held-synchronizing component, which are of opposite polarity and correspond to the initiation of the retrace and trace of the field scansions, respectively. The resultant wave, therefore, may be utilized to energize the synchronizing circuit of the field-scanning generator l8, thereby to synchronize this generator at the initiations-oi both the traceand retrace-scanning periods.

Thus, the arrangement of Fig. 1 comprises a television receiver synchronizing system for utilizing the composite synchronizing signal of Fig. 3, curve A, having recurrent line-synchronizing pulses L and recurrent groups of field-synchronizing pulses F. Field-frequency generator ll includes a synchronizing circuit which responds to pulses of opposite polarity corresponding to the initiations of trace and retrace scanning periods of its scanning cycle, whereby the generator is synchronized at such times. It will be apparent, therefore, that the field-synchroniz ing generator it! includes means adapted to synchronize the generator at the initiations of at least one scanning period, such as the retrace scanning period of such cycle. Additionally, it will be seen that. synchronizing-signal separating means l9 derives a synchronizing pulse, indicated Siin curve C of Fig. 3, from only the first one of the pulses of each of the recurrent groups of field pulses, this derived pulse being adapted to control the synchronizing of the retrace scanning period of generator i8. tending from unit is to generator I8 provides means for applying such derived pulses Sr to the synchronizing circuit in order to control the synchronization of retrace scanning periods of the generator.

As is well understood, scanning-wave generators of the types conventionally utilized are synchronized by the application of control pulses thereto just prior to the points of time when they would otherwise independently commence the parts of the cycle of operation which the control pulses initiate. Except for a small portion of a cycle immediately prior to these points of time, the generators are insensitive to control pulses so that, in the case 01' field-scanning generators, any line-synchronizing components which are not suppressed and which are substantially displaced from the field-synchronizing components do not interfere with the proper syn- 'chronization of the field-scanning generator. Where the composite wave does not include 11- ternate pulses it will be appreciated that a delay of a full line-scanning period or an integral multiple of such period, instead of a half-line scanning period as illustrated by curve B in Fig. 3,

will result in suppression 0! all of the line-synchronizing components. Moreover, a full lineperiod delay may, if desired, be utilized in such a wave as illustrated by curve A in Fig. 3, the

only diflerence in the result being that all the line-synchronizing and alternate pulses, except an alternate pulse at the beginning and end of the period during which the-alternate pulses occur, are suppressed and each of the single pulses Siand St is replaced by a field-synchronizing pulse and an adjacent alternate pulse of the same polarity.

The inventionmay thus be utilized with variousdiflerent types of composite synchronizing The coupling ex- .min'als of the filter 33.

signals and its operation is independent of the relative wave forms of the line-synchronizing and field-synchronizingcomponents of the signal: that is, their durations, plitudes.

In Fig. 4 curve A illustrates the wave form of waveforms, or ama composite synchronizing signal of a particular type which can be utilized only with the separating system of the present invention. Here the field-synchronizing pulses F are of lesser amplitude than the line-synchronizing pulses, so that they cannot be separated by an amplitudeclipper type of amplitude limiting means. Moreover, these pulses have areas and durations comparable to those of the line-synchronizing pulses so that integrating and duration-respons ive devices are not suitable for effecting the separation. For this type of signal the delay circuit of the system of the present invention is proportioned to effect a delay equal to one linescanning period or an integral multiple thereof.

The delayed-reversed-polarity wave, as developed by the system and applied to the combining means, is illustrated by curve. 13, while curve C illustrates the resultant derived wave with the line-synchronizing pulses suppressed.

In the event thatthe delay period is not precise, so that the undesired pulses are not com-- pletely neutralized, narrow vestiglalundesired components in the. resultant wave maybe effectively lay-passed by the capacitance 23a, since most of the'energy of such components is con centrated in the relatively high-frequency components. Capacitance 23a, therefore, comprises means for dissipating residual diiferencepulse's- I from the combining means circuit of tubes 20 and I3. Likewise, theinventlon may be embodied in including the output various dlflerent types of filter-delay apparatus.

One example of a modified form of the apparatus I! of Fig. 1 is shown in Fig. 2. Here the apparatus comprises a single input tube 32 and the ilected an. The resistor 34 terminates the filter at the input terminals inlits image impedance so that there is no further reflection of the echo or reflected wave. Since the filter is shortclrcuited at'its remote end, the reflected wave is of opposite polarity to that of the original wave, and. hence, the applied and delayed waves in this case have the same wave forms and phase relation as in the system of Fig. 1 and as illustrated by curves A andB of Fig. 3. Moreover, the resultant wave developed across the-resistor II, which comprises a combination of the delayed and undelayed waves, is as illlustrated by curve'Cin Fig. 3 and may be applied by a suit-- able lead ll directly to the synchronizing circuit of the field-frequency generator.

{The operation of the system of Fig. 2 may be considered from another aspect with reference,

to Figs. 5, 6, and 7. It will be appreciated that the synchronizing pulses are represented in 'the composite signal by frequency components including a. fundamental frequency component of.

for example, 60 cycles in the case of the fieldfrequency pulses as well as harmonic-frequency components of 120'cycles, 240 cycles, 480 cycles.

etc., in the case mentioned.

I Fig. 5 is a frequency scale, indicating at F: the

fundamental frequency of a field-synchronizing pulse, at 2Fi, an, etc., its progressively higher harmonic frequencies, and indicating at F1 a related fundamental frequency omline-synchronizing pulse and at 2F1, 3F1, etc its progressively I higher harmonic frequencies.

The. circuit 33 of Fig. 2 is essentially a twoterminal filter network which couples the tube 32 to the synchronizing or input circuit of the field-frequency scanning-wave generator. ,In .the absence of the resistor M, the input impedance delay, polarity-reversing, and combiningmeans are embodied in a single dead-end filter circuit indicated generally at 38. The tube 32 may be similar to the tube 2i of Fig. 1 and the filter circuit is coupled across the load resistor Ila thereof by a condenser a. The clrcuit ll comprises a low pass filter including input terminals across which a terminating resistor 34 is corinected and to which is coupled an m-derived half-section including a series'arm comprising an inductance 35 and a shunt arm comprlsinga series-connected inductance 36 and condenser 31, and a series of constant-k whole sections individually comprising series-inductance arms 38 and shunt-condenser arms 39, and an additional series-inductance arm 38a. The filter is shortcircuited at the remote terminals, as indicated In the operation of the system of Fig. 2, the compositesynchronizing signal is applied. to the input electrodes of the tube 32, is repeated in its of the clrcult'33 is a pure reactance which varies with frequency between plus and minus infinity,

as illustrated by the curve of Fig. 6. This figure is not drawn to scale, but is merely intended to show the critical points.

I Such a system, as shown, inherently has zero reactance at a particular fundamental frequency and multiples thereof and it behaves as a family of resonant traps connected in parallel branches. It is wellknown equivalent of an idealreflecting' trans- With the resistor 34 connectedmission line. I across the circuit,as shown, the impedance characteristic of the circuit assumes the form illustrated by the curve of Fig. 7. The circuit thus behaves as a multiple band filter which suppresses or eliminates a particular fundamental frequency component, inv the present case, the

' line-synchronizing fundamental frequency comoutput circuit, and is applied to the input ter-,

Due to-the fact that there is an improper termination or mismatching at the end of the filter remote from, the input terminals, an electrical wave which is the image of the applied wave is reflected from the shortcircuited terminals and appears, after a pre determined delay, across the input terminals.

The time delay of the filter is made one-half'of the'deslred time delay, for example, a quarter of a line-scanning period, to. effect a desired delay of one-half a line-scanning period in the reponent and its harmonic-frequency, components.

While filter systems have heretofore been-besigned for attenuating the line-frequency components of a composite signal in order to effect separation of they field-frequency pulses, in these systems low-passillters have'been provided having a cutoff frequency slightly less than the linefrequency fundamental component. Such arrangements have necessarily suppressed the high harmonic-frequency components of the field-synchronizing pulses which are essential components of field-synchronizing pulses of'the desiredrectangular wave form. The arrangement of the present invention, however, while attenuating the fundamental as well as the harmonic-frequency components of the linesynchronizing pulses leaves allof the higher harmonic frequency as well as the fundamental components of the field-synchronizing pulses,

- excepting the few which may be coincident with a field-frequency certain of the line-synchronizing components.

Here, therefore, separation of the field-frequency aasoo ity of the delayed signal with reference to said composite signal, means for combining the dethose skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is therefore, aimed in the appended claims to cover all such cahnges and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing and field-synchronizing components of the same polarity, comprising a synchronizing circuit for a scanning-wave generator adapted to be energized by one type of said components, means for delaying said composite signal for a predetermined period such that certain of said synchronizing components of the other type substantially coincide in time with corresponding components oi said composite signal without substantially changing the wave form of the delayed signal and for reversingthe relative polarity of the. delayed signal with reference to said composite signal, means for combining the delayed-reversed-polarity signal with the undelayed signal to develop a resultant signal comprising eflectively separated synchronizing comother type suppressed, and means coupling said i combining means to said synchronizing circuit.

layed-reversed polarity signal with the undelayed signal to develop a resultant signal comprising effectively separated field-synchronizing components with at least certain of the linesynchronizing and alternate components suppressed, and means coupling said combining means to said synchronizing circuit.

'4. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing and field-synchronizing components of the same polarity, comprising a synchronizing circuit for a field-frequency scanning-wave generator, means for delaying 'said composite signal for a'prede termined period equalto the duration of a linescanning period without substantially changing the wave form of the delayed signal and for reversing the relative polarity of the delayed signal with reference to said composite signal, means for combining the delayed-reversed-polarity sig- I nal with the undelayed signal to develop a re- 2; A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing and field-synchronizing components of the same polarity, comprising a synchronizing circuit for scanning-wave means Iordelaying said composite signal for a predetermined period such that certain of said line-synchronizing components substantially coincide in time with corresponding components generator, 4c

of said composite signal without substantially changing the wave form of the delayed signal and for reversing the relative polarity of the delayed signal with reference to said composite signal, means for combiningjhe delayed-reversed-polarity signal with the undelayed signal 'to-develop a resultant signal comprising effectively separated field-synchronizing components with at least said certain oi. the line-synchronizing components suppressed, and means coupling said combining means to saidsynchronizing circuit.

3. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing and field-synchronizing components and alter- 6o nate pulse components between line-synchroniZ-- ing components adjacent said field-synchronizing components, all of said pulses having the same polarity, comprisinga synchronizing circult for a ileldirequency scanning-wave gener- 7o iayed signal and for reversingthe relative polarsultant signal comprising effectively separated synchronizing components suppressed, and means couplingsaid combining means to said synchronizing circuit.

5. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing and field-synchronizing components ot'the same polarity, comprising a synchronizing circuit for a field-frequency scanning-wave generator,

means for delaying said composite signal for are predetermined period equal to the duration of an integral multiple of a one-half line-scanning period without substantially changing the wave form of the delayed signal and for reversing the relative polarity of the delayed signal with relerence to said composite signal, means for combining the delayed-reversed-polarity signal with the undelayed signal to develop a resultant sig- 'nal comprising efiectively separated fleld-synchronizing components with at least certain of the line-synchronizing components suppressed, and means coupling said combining means to said synchronizingcircuit.

6. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing components and field-synchronizing components corresponding in frequency to scanning periods and of the same polarity, comprising a synchro nizing circuit for a field-frequency scanningwave generator adapted to be energized at the initiations of both traceand retrace-scanning periods by pulses of opposite polarity, means for delaying said signal for a' predetermined fraction of the duration of said field-synchronizing components such that certain of said line-synchronizing components substantially coincide in time with corresponding components of said composite signal without substantially changing the wave form of the delayed signal and for reversing the relative polarity of the delayed signal with reference to said composite signal, means for combining the delayed-reversed-polarity sigfield-scanning periods with at least certain of said line-synchronizing components suppressed.

and means coupling said combining means to said synchronizing circuit.

'7; A television receiver synchronizing. system comprising an input circuit adapted to have impressed thereon a composite synchronizing signal including recurrent line-synchronizing and field-synchronizing components of the same polarity, comprising a synchronizing circuit for a scanning-wave generator adapted to be energized by one type of said components, means coupled to the said input circuit for delaying said composite slgnalior a predetermined period such that certain of said synchronizing components of the other type substantially coincide in time with corresponding components of said composite signal without substantially changing the wave form of the delayed signal and for revers-.

ing the relative polarity oi the delayed signal,

with reference to said composite signal, a com-' bining circuit coupled to said delay and reversing means and to said input circuit for combining the delayed-reversed-polarity signal with the undelayed signal of opposite polarity to develop a resultant signal comprising effectively separated synchronizing components of said one type with translated by said one channel with the unde layed signaltranslated by the other channel to I develop a resultant signal comprising effectively "separated field-synchronizing components with at least said certain of the line-synchronizing components suppressed, and means coupling said output circuit to said synchronizingcircuit.

, 10. A television receiver synchronizingsystem adapted ior'utilizing a composite synchronizing signal including recurrent line-synchronizing and field-synchronizing components of the same polarity, comprising a synchronizing circuit for a held-frequency scanning-wave generator, an

input circuit adapted to. have said composite.

signal impressed thereon, a dead-end filter network having its input terminals coupled to said \input circuit and adapted to reflect said comat least said certain of the components of the" combining circuit to said synchronizing circuit.

8. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing and field-synchronizing components of the same polarity occurring during predetermined recurrent scanning intervals, comprising a synchronizing circuit for a, field-frequency scanningwave generator adaptedto be energized at. the initiation of traceand retrace-scanning periods by pulses of opposite polarity, means for delaying said composite synchronizing signal for a predetermined period such that certain of said line-synchronizing components substantially coincide in time with corresponding components of said composite signal without substantially changing the wave form 01' the delayed signal and for reversing the relative polarity of the delayed signal with reference to said composite signal, means foricombining the delayed-reother type suppressed, and means coupling said posite signal with a predetermined time delay such that certain of said line-synchronizing com-.-

ponents' substantially coincide in time with corresponding components of said composite signal without substantially changing the wave form or the delayed signal and'a reversal in its polarity, an output circuit coupled to saidfilter network input terminals for deriving a resultant signal comprising .a delayed-reversed-polarity signal combined with the undelayed signal providing eil'ectively separated held-synchronizing components, and means coupling said output clr-- cult to said synchronizing circuit.

11. A television receiver-synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing and field-synchronizingcomponents of the same polarity comprising a synchronizing circuit for a fleld i'requency scanning-wave generator,

' means for delaying said signal for a predetermined period substantially equal to the duration of a one-halt line-scan-= versed-polarity signal' with the undelayed signal of opposite polarity to develop a resultant signal comprising eflectively separated ileld-Irequency synchronizing components each including pulses of oppositepolarity corresponding tothe initiations oi traceand retrace-scanning periods with at least said certain of the line-synchronizing pulses suppressed, and means i'or coupling said combining means to said synchronizing circuit. v c e 9. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing and field-synchronizing components of the same polarity, comprising a synchronizingcircult for afield-frequency scanning-wave generator, an

input circuit, a pair of signal-translating, channels connected. in parallel to said input circuit, one or said channeLs comprising a filter network fol-delaying said signal for a predetermined periodsuch that certain'ot said line-synchronizing components substantially coincide in timefwith components of said compositesigcorresponding without substantially changing the wave ionn otthe delayed signal and means for rethe polarity of said delayed signal, a

output circuit. for saidchan'nals tor m dolayed-reversed-polariw of an integral multi nins period without bstantially changing the wave form of the delayed signal and i'or reversing the relative polarity of the delayed signal with reference to said composite signal, means for combining the delayed-reversed-polarity signal with the undelayed signal to develop a resultant signal comprising eflectively separated fieldsynchronizing components with at least said certain or the line-synchronizing components suppressed, means for dissipating residual diflerence pulses from said combining means, and means coupling said combining means to said synchronizing circuit. I g

.12. a television receiver synchronizing system comprising an input circuit adapted to be energized by a composite synchronizing signalincluding recurrent line-synchronizing and fieldsynchropizing pulses having fundamental and harmonic -frequency components, a'synchronizing circuit for a field-frequency scanning-wave generator adapted to be energized by said field-- synchronizing pulses, and frequency-selective means coupling said synchronizing circuit tosaid input'circuit responsive to components of said field-synchronizing pulses including the fundamental component and at least one harmonic component of a frequency higher than the'tundamental frequency component of the line-synchronizing pulses, said frequency-selective means being also substantially unresponsive-to a plurality of said line-synchronizing components'including the fundamental frequency component thereoL,

13. Atelevision receiver synchronizing system i comprisi'm an input circuit adapted to be energinedhyacompositesynehroniling muslin-- eluding recurrent and fieldcacao erator adapted to be energized by said field- I synchronizing pulses, and frequency-selective means coupling said synchronizing circuit to said input circuit effective substantially to suppress line-synchronizing pulse fundamental and harmonic-frequency components without substantially attenuating adjacent field-synchronizing harmonic-frequency components above and below said line pulse fundamental component.

14. A television receiver synchronizing system comprising an input circuit adapted to be energized by a composite synchronizing signal including recurrent line-synchronizing andfleldsynchronizing pulses having fundamental and harmonic-frequency components, comprising a synchronizing circuit for a scanning-wave generator adapted to be energized by one of said,

types of pulses, and means coupling said synchronizing circuit to said input circuit comprising a multiple band-pass filter responsive only to synchronizing pulse components of said one of said types including the fundamental component thereof and at least one of the harmonic components thereof separated from said fundamental frequency component by one or more components of the pulses of said other type.

15. A television receiver synchronizing system comprising an input circuit adapted to be energized by a compositesynchronizing signal including recurrent line-synchronizing and heldsynchronizing pulses having fundamental and harmonic-frequency components, comprising a synchronizing circuit for a scanning-wave gencrator adapted to be energized by said fieldsynchronizing pulses, an input circuit adapted to be energized by said composite signal, and means coupling said synchronizing circuit to said in put circuit comprising a multiple band-pass filter for translating said signal adapted substantially to suppress said line-synchronizing fundamental frequency componentswithout substantially attenuating adjacent field-synchronizing pulse harmonic-frequency components.

16. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing pulses and recurrent groups of field-synchronizing pulses comprising, pulse-responsive means for synchronizing a field-scanning wave generator at the initiations of at least one scanning period nization of said one scanning period of said gen-' erator;

18. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing pulses and recurrent groups of field-synchronizing pulses comprising, pulse-responsive means for synchronizing a field-scanning wave generator at the initiations of at least one scanning period of a scanning cycle, synchronizing-signal separating means for deriving at least one pulse of a scanning cycle, synchronizing-signal separating means for deriving a single pulse from only a particular one of the pulses of each of said recurrent groups of pulses which is adapted to control the synchronizing of said one scanning period, and means for applying said derived pulses to said synchronizing means to control the synchronization of said one scanning period of said generator.

17. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing pulses and recurrent groups of field-synchronizing pulses comprising, pulse-responsive means for synchronizing a field-scanning Wave generator at the initiations of at least one scanning period of a scanning cycle, means for applying pulses corresponding to at least said recurrent groups of pulses to said synchronizing means, and means for causing said synchronizing means to be rerecurrent groups of pulses to control the synchrofrom each of said recurrent groups of pulses and forapplying said derived pulses to said synchronizing means to control the synchronization of saidgenerator, and means included in one of said aforementioned means for causing said synchronizing means to be responsive only to a particular pulse of each of said recurrent groups of pulses to control the synchronization of said one.

scanning period of said generator.

19. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing pulses and recurrent groups of field-synchronizing pulses comprising, pulse-responsive means for synchronizing a field-scanning wave generator at the initiations of at least one scanning period of a scanning cycle, synchronizing-signal separating means for deriving at least one pulse from each of said recurrent groups of pulses and for applying said derived pulses to said synchronizing means to control the synchronization of said generator, and means included in one of said aforementioned means for causing said synchronizing means to be responsive only to the first pulse of each of said recurrent groups of pulses field-synchronizing pulses of the same polarity comprising, pulse-responsive means for synchronizing a field-scanning .wave generator at the initiations 'of at least one scanning period of a scanning cycle, synchronizing-signal separating means for deriving at least'one pulse from each of said recurrent groups of pulses and for applying said derived pulses to said synchronizing means, and means included in one of said aforementioned means ior causing said synchronizing means to be responsive only to a particular pulse of each of said recurrent groups of pulses to control the synchronization of said one scanning period of said generator.

21. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent, line-synchronizing pulses and recurrent groups of field-synchronizing pulses comprising, pulse-responsive means for synchronizing a field-scanning wave generator at the initiations of at least one scanning queried of a scanning cycle, synchronizing-signal separating means for deriving at leasi one pulse from each of said recurrent groups of pulses and for applying said derived pulses to said synchronizing means to control the synchronization of said generator, and means included in said synchronizing-signal separating means for causing said synchronizing means to be responsive only to a particular pulse of each of said recurrent groups of pulses to control the synchronization of said one scanning period or said generator.

22. A television receiver synchronizing system adapted tor'utilizing a composite synchronizing "signal including recurrent line-synchronizing pulses of one polarity and recurrent groups of field-synchronizing pulses of the same polarity comprising, pulse-responsive means. for synchronizing a field-scanning wave generator, means i'or delaying said composite signal for a predetermined period such that certain ofsaid linesynchronizing pulses substantially coincide in time with corresponding pulses of the composite signal without substantially changing the wave form of the delayed signal and for reversing the relative polarity of the delayed signal, means for combining the delayed-reversed polarity signal with the undelayed signal to develop a resultant signal comprising at least one pulse which corresponds to a particular pulse of each of said group of pulses, and means for applying said resultant signal to said synchronizing means to cause said generator to be synchronized in response to said particular pulse. 1 i

23. A television receiver synchronizing system adapted for utilizing a composite synchronizing signal including recurrent line-synchronizing pulses of one polarity andrecurrent groups of field-synchronizing pulses of the same polarity comprising, pulse-responsive means for synchro-' nizing a field-scanning wave generator at the "initiations of at least one scanning period 01' a means for deriving at least one pulse from each scanning cycle, synchronizing-signal separating of said recurrent groups or and for applye ing said derived pulses to said synchronizing means to control the synchronization of said generator, and frequency-selective means included in said synchronizing-signalseparating means for causing said synchronizing means to be responsive'only to aparticular pulse of each or said recurrent groppsiot pulses to control the synchronizatlon of said one scanning period of said gen- "erator.

24. A television receiver synchronizing system adapted forutilizing a composite synchronizing signal including recurrent line-synchronizing pulses of one polarity and recurrent groups of field-synchronizing pulses oi! the-same polarity comprising, pulse-responsivemeans for synchro-y nizing a field-scanning ,wave generator'at the initiations of at least one scanning period of a scanning cycle, synchronizing-signal separating means for deriving at least one pulse from each or said recurrent groupsot pulses and for applying said derived pulses to said synchronizing means to control the synchronization of said genorator, and a multiple band-pass filter included in said synchronizing-signal separating means for causing said synchronizing means to be responsive only to a particular pulse of each of said recurrent groups of pulses to control the synchronization of said one scanning period of said generator.

HAROLD M. LEWIS. 

